The objectives of our research efforts are directed to elucidate the molecular basis for both the genetic and environmental factors influencing mutagenesis. The main hypotheses on which our research efforts are directed are: (1) mutagenesis in mammalian cells is the result of genetic and biochemical control (e.g., DNA repair enzymes) and (2) mutagenesis is a major component of carcinogenesis. Specifically, with the use of environmental chemicals which are either known tumor promoters or inhibitors, we will analyze their effect on DNA repair and mutagenesis. Concomitantly, we will examine the spontaneous and induced mutation frequencies of cells derived from genetically-deficient individuals predisposed to cancer.